Problem: Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Kevin needs to master at least $159$ songs. Kevin has already mastered $40$ songs. If Kevin can master $6$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
Answer: To solve this, let's set up an expression to show how many songs Kevin will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Kevin Needs to have at least $159$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 159$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 159$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 6 + 40 \geq 159$ $ x \cdot 6 \geq 159 - 40 $ $ x \cdot 6 \geq 119 $ $x \geq \dfrac{119}{6} \approx 19.83$ Since we only care about whole months that Kevin has spent working, we round $19.83$ up to $20$ Kevin must work for at least 20 months.